Many medicament delivery devices are developed for self-administration, i.e. a user performs the medicament delivery her-, or himself. This requires a medicament delivery device, which is reliable, accurate, safe and easy to use. In order to meet these requirements, the risk of human errors must be minimized, the number of actions needed to be performed in order to receive a dose need to be reduced and the device must be intuitive to use. Thus, in order to minimize the risk of human errors, it is desirable to have a device that accurately provides a user with confirmation that he/she has received a complete dose of medicament.
Medicament delivery devices such as injection devices providing automatic or manual delivery member insertion, automatic injection of a medicament, automatic delivery member retraction or automatic covering of the delivery member are known in the art. Though these injection devices provide many benefits, there is always room for improvement. For example, a device that provides both a complete delivery of medicament and release of a member that produces a reliable audible and/or tactile and/or visible confirmation to the user that the delivery has been completed has hitherto required extremely tight tolerances during manufacturing.
For example, release of a member that produces a reliable audible and/or tactile and/or visible confirmation to the user that the delivery has been completed is disclosed in WO2011043714A1. The release is accomplished by disengaging a plunger rod from a second activator member once the plunger rod has terminated its displacement for delivering the medicament. The termination of the plunger rod displacement and the disengaging of the plunger rod from the second activator member must occur simultaneously if both a complete delivery of a medicament and a release of the second activator member which produces the reliable audible and/or tactile and/or visible confirmation to the user that the delivery has been completed are to be accomplished.
Thus, in WO2011043714A1 there is only one mechanical position that is used to activate the release of the second activation member at the point where it is expected that the plunger displacement will terminate. The precision of the timing of the termination of plunger displacement and disengagement of the plunger from the second activation member relies on the manufacturing and assembly dimensions of the parts of the device and thus the tolerances play an important role in the proper functioning of the device.
Thus, in order to compensate for component tolerances a signal generating member needs to be released before the plunger displacement has terminated. A user may then be prone to remove the device from the delivery site, accidentally causing interruption of the medicament delivery. In order to ensure a complete and accurate delivery of a medicament, all the parts or components of the device must be manufactured to very tight tolerances, leading to high manufacturing and assembling costs.
Thus, it would be an improvement in the art to provide a medicament delivery device that can be manufactured and assembled, having reliable functions, such as a complete delivery of a medicament followed by an audible and/or tactile and/or visible confirmation to the user that the delivery has been completed.